When a spring-receiving hole for supporting a lower end of a valve spring of an intake valve and an exhaust valve is recessed in an upper face of an engine cylinder head, there is the problem that oil that has lubricated a valve operating mechanism builds up in the spring-receiving hole and cannot be discharged. An arrangement in which an oil guide channel is made to run through a bridging part that projects so as to be a barrier between the spring-receiving hole and an oil drop hole formed in a side edge of a cylinder head, and oil that has collected in the spring-receiving hole is discharged to the oil drop hole via the oil guide channel is known from Patent Publication 1 below.    Patent Publication 1: Japanese Patent Application Laid-open No. 4-112910